The present invention relates to pulse forming systems, and more particularly high energy, short duration systems. Such systems find application with spark gaps, or in a variety of pulse networks.
Light activated semiconductive devices are well known in the art, ranging from light activated rectifying diodes to light activated thyristors. Such light activated semiconductive devices have been used with fast rise time pulse lasers to switch on very high currents in a few nanoseconds or less. It has not yet been possible to turn off such semiconductive devices in comparably short times, because the time required to turn off the device is related to the time required to sweep out current carriers from the semiconductive device, or for recombination to eliminate these current carriers.
A conventional way of protecting high voltage power supplies, or of delivering energy pulses from such sources is to use a "crowbar" parallel shunting circuit with a high power switching device such as a thyratron activated ignitron as the switch element. Of course, such prior art systems had relatively long turn-on times and resultant long pulse times.
Light activated semiconductive devices are well known in the art, as in U.S. Pat. Nos. 3,585,454 and 3,832,732. These devices can be rapidly activated with turn-on times largely limited by the rise time of the light source. Recently developed pulse lasers have rise times of several nanoseconds, with pulse widths of tens of nanoseconds, such as a YAG laser.